Solid state lighting devices have been used to provide energy savings in lighting power consumption due to the increased efficiency of their source. However, solid state lighting devices known in the art may be expensive and may have insufficient operational life to offset their higher costs.
In most commercially available LED bulbs, approximately 75-85% of the electrical power delivered to the bulb may be immediately converted to heat. This heat may limit the operational life of the device. For example, the insulating dielectric typically used in the electrolytic capacitors of LED driver and rectification/regulation circuitry may desiccate rapidly with exposure to the thermal cycles that currently available LED bulbs undergo. Capacitor mortality thus may be a significant problem in existing LED bulb technology.
One example of a currently available LED bulb for residential/commercial use would be the EcoSmart Model ECS38 LED bulb 100 (see FIG. 1), which can consume 18 W of electrical power and can provide a light output of 850 lumens, which is about the equivalent of a 60 W incandescent bulb. The bulb 100 utilizes passive fins, e.g. fin 112 to dissipate heat generated by the light source 120. The total internal power dissipation of the ECS38 bulb may be about 16 W, which can result in a package temperature rise of 23° C. above ambient (measured at the coolest point on the finned aluminum heat sink, which may be at the perimeter 114 of the heat sink which is farthest away from the heat source), corresponding to a heat sink thermal resistance of 1.4° C./W.
Furthermore, blue LEDs are typically used in most residential/commercial lighting applications, in which case the blue light emitted is first converted to white light. However, this conversion process may impose further inefficiencies in currently available LED bulbs.